1. Field of the Invention
The present invention relates to aerosol generation and, in particular, to a device that is useful for the production of high volumes of non-toxic simulated smoke for industrial use, military use, and the like.
2. Description of Related Art
The generation of a synthetic smoke has been used by the military during combat and training exercises. In addition, it is used by fire departments and police departments for their needs. On the industrial side, theater and motion picture companies frequently use synthetic smoke to simulate smoke for special effects. Typically, these larger uses involve passing a pressurized, smoke producing liquid near a heat source which vaporizes the liquid into a smoke gas. Usually non-toxic, the formulations can be oil or water based depending on the use and the desired effect. The heat source is usually either battery powered or a flame powered by an ignitable gas, such as liquid propane gas (LPG). The smoke producing liquid is usually pressurized by use of some gas that is inert in the process, such as air nitrogen or the like.
In use, the heating source is heated to a given temperature and then the pressurized, smoke producing liquid passes near the heat source vaporizing before exiting a spray or atomizing nozzle of some sort. Because the vaporization of the smoke producing liquid drains heat energy from the heat source, the problem that exists with these devices is that they can only be used for relatively short bursts since heating the liquid also cools the heat source. This is especially true with battery operated heat sources, and even gas fired heat sources have limited capacity to heat before cooling. In addition, smoke generators typically have limited operational capacity for smoke producing liquid prior to replacing the source or refilling them with additional fluid. An example of a device with such problems is exemplified in U.S. Pat. No. 4,998,479 to Perham et al., issued Mar. 12, 1991 which uses a gas burner in an ignition chamber and discharges the smoke generating gas through a heating coil having about 4 turns. The device has limited capacity for gas generating liquid and is only operable for short bursts before cooling below the vaporization temperature of smoke producing liquids since the heat chamber cools very quickly. In addition, the device cannot generate a dense, thick cloud of smoke as is necessary for many industrial uses. A further problem with this and other devices where an ignition spark ignites a gas, is that ignition is very haphazard and igniting the gas can take several tries leading to a dangerous explosive situation if too much gas accumulates in the ignition chamber before the gases ignite.